Gigabyte motherboards can use 'EasyTune 6'.Universal abit motherboards can use 'μGuru'.MSI motherboards can use 'Core Center'.ASUS motherboards can use 'Fan Xpert' or 'Thermal Radar'.AOpen motherboards can use 'SilentTEK'.Many companies now provide software to control fan speeds on their motherboards under Microsoft Windows or Mac OS X/MacOS. The method by which the software physically controls the fan is usually PWM (see above). A variable rotation speed allows the cooling rate to be adjusted to meet demand, quietening the fan and saving energy when full speed is not required. Fan assemblies with this control input provide the ability to adjust the rotational speed of the fan without changing the input voltage delivered to the cooling fan assembly. Control input – a pulse-width modulation (PWM) input signal, used when the cooling fan assembly has an internal motor driver circuit.

Sense (or tachometer) output from fan – outputs a signal that pulses twice for each rotation of the fan as a pulse train, with the signal frequency proportional to the fan speed.

Vcc (Power) – nominally a +12 V supply, though it may be variable depending on fan type and desired fan rotation speed.

The first two pins are always used to deliver power to the fan motor, while the rest can be optional, depending on fan design and type: The common cooling fans used in computers use standardized connectors with two to four pins.

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